This invention relates to a paper feeder used with a recording apparatus such as a printer for feeding sheet-like paper stacked on a hopper, and in particular to a paper feeder comprising a paper returner for returning an overlappedly transported sheet of paper to the hopper, the paper returner having a function of separating and feeding sheets of paper one by one.
A paper feeder used with a recording apparatus comprises two paper feeding rollers placed in a paper width direction, the one paper feeding roller being fixedly placed on one side edge side, and the other being built in an edge guide and semi-fixedly placed movably matching the paper width. A base end of the hopper is attached rotatably to a shaft at a right angle to the entry direction such that the whole of paper in the width direction is moved up or down at the same time by a cam mechanism associated with rotation of the paper feeding roller. A rotatable separation pad holder is provided with a separation pad to separate the sheets one by one from the hopper and feed each sheet.
When paper is abutted against the paper feeding roller, and at the same time, the separation pad is pressed against the paper feeding roller as the hopper moves up, the top sheet of paper is separated and fed. When the sheet arrives at a transport roller and skew removal is terminated, the paper feeding roller is rotated and stopped at a home position. Meanwhile, positioning is performed such that a distance between a leading edge of the paper sheet and a recording head is made constant is performed, and then print is started. When the paper feeding roller is stopped at the home position, a gap is formed between the paper feeding roller and the separation pad, but a part of the sheet being printed exists. At this time, another sheet overlappedly sent enters the gap, and two or more overlapped sheets may also be fed in conjunction with the sheet being printed in some cases. As a measure against such trouble, an idle roller is usually pressed against the separation pad. When a sheet being printed exists between the paper feeding roller and the separation pad, it is pressed against the separation pad by the idle roller, whereby entry of the sheets overlappedly sent is prevented. Each sheet whose entry is blocked is pushed and returned to the hopper by operating a paper return lever (paper returner) after the print terminates.
This related paper feeder comprises the separation pad holder and the paper return lever as separate components, and thus has a complicated structure and a large number of parts, leading to an increase in costs. Since the paper returning operation is performed after print, the next paper feed operation cannot be started until the paper returning operation terminates, and thus the time interval between the print termination of one sheet and the print start of another sheet (throughput) is prolonged. Further, since the sheet being printed is pressed against the idle roller, a contact load with the sheet occurs and leads to a load of a motor drive system, etc.
It is therefore an object of the invention to provide a paper feeder comprising a paper returner provided with a function of surely separating and feeding sheets of paper one by one.
It is another object of the invention to provide a paper feeder capable of performing the paper returning operation during printing.
In order to achieve the above objects, according to the present invention, there is provided a paper feeder, for feeding a sheet of paper to a recording apparatus, comprising:
a hopper, for stacking a plurality of sheets of paper;
a paper feeding roller, which constitutes a part of a paper transporting passage;
a paper returner, placed in the vicinity of an end portion of the hopper which faces the paper feeding roller, so as to be pivotable between a first position where the paper returner constitutes a part of the paper transporting passage, and a second position where the paper returner is isolated from the paper transporting passage; and
a separation pad, provided on a first face of the paper returner, the separation pad having a friction coefficient which is higher than a friction coefficient of the first face of the paper returner,
wherein the paper returner is placed at the first position so that a top sheet of paper in the hopper is abutted against the paper feeding roller, and is separated from other sheets of paper by the separation pad; and
wherein the paper returner is placed at the second position so that the first face of the paper returner returns sheets of paper, which are entered in the paper transporting passage together with the sheet of paper to be fed, to the hopper.
In this configuration, since the separation pad is attached to the paper returner, so that the number of parts can be decreased and the structure can be simplified for reducing costs as compared with the case where the separation pad holder and the paper return lever are provided separately as in the related paper feeder.
Preferably, the paper feeder further comprises an auxiliary roller. Here, the paper feeding roller and the auxiliary roller are arranged in a widthwise direction of the sheet of paper. The first face of the returner abuts the top sheet of paper are abutted against the paper feeding roller and the auxiliary roller, when the paper returner is placed in the first position.
In this configuration, motion of the opposite end of paper with no caught entry by the paper feeding roller is suppressed and skew is hard to occur and can be prevented from causing a paper jam to occur.
Preferably, the first face of the returner prevents the sheets of paper in the hopper from entering the paper transporting passage, when the paper returner is placed in the second position.
In this configuration, when paper is not fed, the leading end of paper is regulated, and accidental entry of paper into the paper transporting passage can be blocked.
Preferably, the paper feeder further comprises an urging member, which urges the paper returner toward the second position. Here, the paper feeding roller includes a first portion which urges the first face of the paper returner toward the first position, against an urging force of the urging member.
In this configuration, the first face of the paper returner is always abutted against the paper feeding roller, and paper pressing and paper returning operations of the paper returner are made reliable.
Here, it is preferable that the paper feeder further comprises an incliner, which inclines the paper returner from the second position toward the first position at a predetermined angle, so that the first face of the paper returner is urged by the first portion of the paper feeding roller.
In this configuration, the paper returner can be rotated smoothly without straining and the paper transporting passage from the hopper to the paper feeding roller is almost closed by the paper returner, so that accidental entry of paper into the paper transporting passage can be blocked.
Here, it is preferable that the incliner is placed other than a widthwise end of the paper transporting passage.
In this configuration, if the incliner operates with jammed paper existing on the paper returner, the paper is not damaged.
Here, it is preferable that the incliner includes a cam cooperated with the paper feeding roller, and a cam follower formed on a part of the paper returner which is projected to the outside of the widthwise end of the paper transporting passage.
In this configuration, the incliner is implemented as the cam mechanism, so that the structure is simplified.
Preferably, the paper feeder further comprises a cam mechanism, which approaches the hopper to the paper feeding roller after the paper returner is placed in the first position.
If the approaching of the hopper to insert the sheet of paper is started while the paper returner is pivoting, there is probability that the leading end of paper is broken by the paper returner. However, in this configuration, the above-mentioned disadvantage can be prevented reliably.
Here, it is preferable that the paper returner starts to move to the second position after the cam mechanism separates the hopper from the paper feeding roller and before the feeding operation of the top sheet of paper is completed.
In this configuration, a sheet of paper transported together with the fed sheet can be returned to the hopper reliably. The operation is performed while paper is being fed, so that throughput is enhanced. Since the paper returner is at the second position during printing, an idle roller for blocking entry of extra paper into the paper transporting passage as in the related paper feeder becomes unnecessary, and the contact load between the paper returner and the paper feeding roller can be decreased.
Preferably, the paper feeding roller is placed in the vicinity of one widthwise end of the paper transporting passage. The hopper is pivotable about one widthwise end portion thereof which is in the vicinity of the other widthwise end of the paper transporting passage.
In this configuration, the longitudinal width of the hopper can be lessened for miniaturizing the hopper, and the number of parts can be reduced because only the paper feeding roller is required.
Preferably, a stacking plane of the hopper is parallel with a tangent plane of the paper feeding roller.
In this configuration, the entry angle into the separation pad does not change and paper is fed stably, even if the number of sheets of paper changes.